Respiratory masks used in the treatment of SDB may comprise a nasal mask, designed to fit over a patient's nose, or a full face mask designed to fit over the nose and mouth of the patient. In both cases, the mask is held in position by headgear.
The mask generally comprises a relatively rigid shell, termed a frame, which defines a rearwardly opening cavity covering the patient's nose and/or mouth and a soft portion, termed a cushion, which spaces the frame away from the face for comfortable contact.
The air or other breathable gas is supplied by a blower and passed along a flexible conduit to the mask. The conduit is typically of relatively large bore, for example approximately 2 cm diameter, with the mask frame having a gas inlet of comparable diameter.
In addition to the gas inlet, the mask may also have CO2 washout vents and one or more small diameter ports through which supplemental oxygen may be introduced or measurements made. The ports typically comprise a pair of cylindrical connectors moulded into the mask frame, usually projecting forward from the front surface of the frame. The mask ports typically also include a cap which prevents leakage of air from the mask when the port is not in use.
Depending on the part construction and the relative diameters of the port and the tubing which supplies supplemental oxygen, the port may function as a male or a female connector.
The Mirage® nasal mask (ResMed Ltd.) is a generally triangular mask with a gas inlet tube extending upwards from its apex. The two ports of that mask are located in the front of the gas inlet tube just above the patient's eye level, between a pair of shield projections. A single cap of silicone rubber covers both ports, and has tabs at either end to facilitate removal by pulling on the tabs in a direction away from patient's face.
There is a need for ports which are conveniently located on the mask, which are protected from accidental breakage and which do not foul tubing. There is a need for a corresponding port cap which is sufficiently large so as to be easy to handle and which is not so small as to be easily lost.